Franken Plane mark II
This project is designed to bring my RC plane back home to me when I cant do it myself.

I fly my electric RC plane (The FrankenPlane Mark II) with First Person Video. This means placing a Camera and 2.4Ghz downlink on the plane and viewing it on a headset or monitor. It’s as close to flying real planes as you get. I get to fly from the perspective of the place in realtime. My problem is that 2.4Ghz video does not travel all that far (relative to RC flight) without high power, directional antennae or tracking systems. If I fly out of range of my receiver, I can completely loose the downlink and literally be flying blind.

What to do? Get the plane to come back!

This project operates under the theory that I lost video due to signal strength, be it flying too far away or out of the receive antennas’ lobe. So if the plane can bring itself back closer, then the downlink should be restored.

Enter Robotics!

I am using a Parallax Propeller (pun not intended but appreciated!) prototyping board to create an Autopilot that can first and foremost, bring my plane back to me. The system consists of the following components:

- RC plane. I use a foam Easyglider with a bolted on electric motor and larger custom cockpit. This is a stabile beginner model
- Main Processor – the Parallax Propeller with 8 cogs that allow me to run interrupt free.
- A GPS chip – send location information once per second to the Processor
- SD card reader – for recording the flight
- An automatic wing leveler. This device checks the horizon based on the heat of the earth against the heat of the sky and determines if the plane is level. It send servo control to the ailerons to set the plane level.

Here’s how it works:

- I power up my R/C transmitter.
- I power up the plane and the GPS gets a fix. This position is recorded to the SD card for reference as the Home location. The processor continuously updates the distance and direction to home even when not enabled.
- Power up the video receiver (located on my ohh-so-stylish hardhat) and video goggles.
- Prepare for launch and start to fly.
- To enable the Return to Home (RTH) autopilot, I flip a switch on the RC transmitter.
- The Processor takes over, gives the plane 50% power, and starts a slow flat turn using the rudder to bring the plane back to Home.

The RC transmitter has a 2-3 mile range and will work well in excess of the video being sent back from the plane, so I don’t have to worry about the RTH signal reaching the processor. I determined that 50% power is enough to keep the plane controlled in most winds and to gain altitude without using the elevator. The system also records the GPS positions to the SD card into a KML file. KMLs can be opened up directly into Google Earth, which is pretty cool.

To do:

- Add a video overlay of all the telemetry data. The data available to me includes groundspeed, altitude, distance and direction home, as well as the servo deflections and other underlying details. I want to do this at the plane rather than transmit the data digitally back to a ground station
- Learn to integrate all the sensor information together and pick the best inputs. I believe a Kalman filter may work, but I’m a slow learner…
- Add the ability to export from Google Earth TO the plane to set a route for the plane to fly.
- Etch a PCB board and build everything – GPS, R/C receiver, battery meter and video overlay – onto a single board. Right now it’s an amalgamation of components.
- And ohh so much more.. like build a tracking groundstation with my steppers and

Overall Status: In Progress.

- The project is Mark II because it has been replaced at least twice over due to wrecks or broken hardware.
- The plane flies, records data, sends video, maintains it’s level attitude (mostly) and can turn based on the GPS commands. However, I am ever learning that the ideal conditions in my mind are often not what a gusty or even mild day can present at any given instant.
- Penultimately and before anyone jumps on me and says “Hey That plane is made of tape!”, know that you are correct. It’s foam, tape, superglue and carbon fiber rods mostly. I thought this hobby was going to be FLYING planes, not repeatedly Remodeling them… Its not my strong point but it works and I stand beside it.
- And finally, <rant> I always get a little grief in R/C forums when I talk about this project so I’ll just say that I am not an AMA (American Modelers Association) member so I am exempt from their visual flight rules. I am very safe and don’t fly over populated areas. I hope no one has a cow over it, but some in the AMA guys seem to think they control all RC aircraft, which they don’t, and like to flame in the forums. </rant>